Flowable dielectric using oxide liner

ABSTRACT

Methods of forming silicon oxide layers are described. The methods include mixing a carbon-free silicon-containing precursor with a radical-nitrogen precursor, and depositing a silicon-and-nitrogen-containing layer on a substrate. The radical-nitrogen precursor is formed in a plasma by flowing a hydrogen-and-nitrogen-containing precursor into the plasma. Prior to depositing the silicon-and-nitrogen-containing layer, a silicon oxide liner layer is formed to improve adhesion, smoothness and flowability of the silicon-and-nitrogen-containing layer. The silicon-and-nitrogen-containing layer may be converted to a silicon-and-oxygen-containing layer by curing and annealing the film. Methods also include forming a silicon oxide liner layer before applying a spin-on silicon-containing material.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Prov. Pat. App. No.61/292,520 filed Jan. 6, 2010, and titled “RADICAL COMPONENT DIELECTRICUSING OXIDE LINER,” which is incorporated herein by reference for allpurposes.

BACKGROUND OF THE INVENTION

Semiconductor device geometries have dramatically decreased in sizesince their introduction several decades ago. Modern semiconductorfabrication equipment routinely produces devices with 45 nm, 32 nm, and28 nm feature sizes, and new equipment is being developed andimplemented to make devices with even smaller geometries. The decreasingfeature sizes result in structural features on the device havingdecreased spatial dimensions. The widths of gaps and trenches on thedevice narrow to a point where the aspect ratio of gap depth to itswidth becomes high enough to make it challenging to fill the gap withdielectric material. The depositing dielectric material is prone to clogat the top before the gap completely fills, producing a void or seam inthe middle of the gap.

Over the years, many techniques have been developed to avoid havingdielectric material clog the top of a gap, or to “heal” the void or seamthat has been formed. One approach has been to start with highlyflowable precursor materials that may be applied in a liquid phase to aspinning substrate surface (e.g., SOG deposition techniques). Theseflowable precursors can flow into and fill very small substrate gapswithout forming voids or weak seams. However, once these highly flowablematerials are deposited, they have to be hardened into a soliddielectric material.

In many instances, the hardening process includes a heat treatment toremove carbon and hydroxyl groups from the deposited material to leavebehind a solid dielectric such as silicon oxide. Unfortunately, thedeparting carbon and hydroxyl species often leave behind pores in thehardened dielectic that reduce the quality of the final material. Inaddition, the hardening dielectric also tends to shrink in volume, whichcan leave cracks and spaces at the interface of the dielectric and thesurrounding substrate. In some instances, the volume of the hardeneddielectric can decrease by 40% or more.

Thus, there is a need for new deposition processes and materials to formdielectric materials on structured substrates without generating voids,seams, or both, in substrate gaps and trenches. There is also a need formaterials and methods of hardening flowable dielectric materials withfewer pores and a lower decrease in volume. This and other needs areaddressed in the present application.

BRIEF SUMMARY OF THE INVENTION

Methods of forming silicon oxide layers are described. The methodsinclude subsequently mixing a carbon-free silicon-containing precursorwith a radical-nitrogen precursor, and depositing asilicon-and-nitrogen-containing layer on a substrate. Theradical-nitrogen precursor is formed in a plasma by flowing ahydrogen-and-nitrogen-containing precursor into the plasma. Prior todepositing the silicon-and-nitrogen-containing layer, a silicon oxideliner layer is formed to improve adhesion, smoothness and flowability ofthe silicon-and-nitrogen-containing layer. Thesilicon-and-nitrogen-containing layer may be converted to asilicon-and-oxygen-containing layer by curing and annealing the film.Methods also include forming a silicon oxide liner layer before applyinga spin-on silicon-containing material.

Embodiments of the invention include methods of forming a flowabledielectric layer on a substrate. The methods include the sequentialsteps of (1) forming a generally conformal silicon oxide liner layer onthe substrate by exposing the substrate to a silicon-containing linerprecursor and an oxygen-containing liner precursor while the substrateis maintained at a liner deposition temperature, and (2) forming acarbon-free flowable silicon-nitrogen-and-hydrogen-containing layer onthe substrate while the substrate is maintained at a bulk depositiontemperature.

Additional embodiments and features are set forth in part in thedescription that follows, and in part will become apparent to thoseskilled in the art upon examination of the specification or may belearned by the practice of the invention. The features and advantages ofthe invention may be realized and attained by means of theinstrumentalities, combinations, and methods described in thespecification.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings wherein like reference numerals are usedthroughout the several drawings to refer to similar components. In someinstances, a sublabel is associated with a reference numeral and followsa hyphen to denote one of multiple similar components. When reference ismade to a reference numeral without specification to an existingsublabel, it is intended to refer to all such multiple similarcomponents.

FIG. 1 is a flowchart illustrating selected steps for making a siliconoxide film according to embodiments of the invention.

FIG. 2 is another flowchart illustrating selected steps for forming asilicon oxide film in a substrate gap according to embodiments of theinvention.

FIG. 3 shows a substrate processing system according to embodiments ofthe invention.

FIG. 4A shows a substrate processing chamber according to embodiments ofthe invention.

FIG. 4B shows a showerhead of a substrate processing chamber accordingto embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Methods of forming silicon oxide layers are described. The methodsinclude mixing a carbon-free silicon-containing precursor with aradical-nitrogen precursor, and depositing asilicon-and-nitrogen-containing layer on a substrate. Theradical-nitrogen precursor is formed in a plasma by flowing ahydrogen-and-nitrogen-containing precursor into the plasma. Prior todepositing the silicon-and-nitrogen-containing layer, a silicon oxideliner layer is formed to improve adhesion, smoothness and flowability ofthe silicon-and-nitrogen-containing layer. Thesilicon-and-nitrogen-containing layer may be converted to asilicon-and-oxygen-containing layer by curing and annealing the film.Methods also include forming a silicon oxide liner layer before applyinga spin-on silicon-containing material.

Introducing an oxide liner layer between a substrate and asilicon-and-nitrogen-containing layer appears to improve adhesion andreduce incidences of delamination and cracking during and aftersubsequent processing. Silicon oxide films formed according to disclosedembodiments using a silicon oxide liner have also exhibited a smootherouter surface indicating a modification in the deposition dynamics.Without binding the coverage of the claims to theoretical mechanismswhich may or may not be entirely correct, silanol groups may be presenton the exposed surface of the silicon oxide liner layer and may serve toincrease mobility thereby increasing nascent flowability of thesilicon-and-nitrogen-containing layer. Other benefits of including asilicon oxide layer include a more rapid initial growth rate on siliconnitride, a common underlying material in some applications. Otherbenefits also include accommodating contraction or expansion of theoverlying layer relative to the underlying substrate. Following thedeposition of the multilayer, the silicon-and-nitrogen-containing layermay be cured and/or annealed in oxygen-containing environments toconvert the layer to silicon oxide.

Additional details about the methods and systems of forming the siliconoxide layer will now be described.

Exemplary Silicon Oxide Formation Process

FIG. 1 is a flowchart showing selected steps in methods 100 of makingsilicon oxide films according to embodiments of the invention. Themethod 100 includes depositing a silicon oxide liner on a substrate withconcurrent flows of TEOS and ozone (O₃) in operation 101. As with otherliner depositions described herein, the substrate temperature duringdeposition is greater than 400° C., greater than 500° C. and greaterthan 600° C. in embodiments of the invention. Additives such as water(H₂O, steam), HMDS and TMDSO may be added to TEOS and ozone (O₃) inorder to ensure a more flowable or smooth deposition. The relativelyhigh temperature of the substrate relative to the radical-componentdeposition which follows facilitates deposition on inert surfaces suchas silicon nitride. The liner then presents a silicon oxide surfacewhich is less inert and more conducive to relatively low-temperaturedeposition. Such deposition processes are known in the art assub-atmospheric CVD (SACVD) but may also be conducted at pressures inexcess of 1 atm. Exemplary flow-rates of TEOS may be greater than 0.1gm/min (grams per minute), greater than 0.5 gm/min, greater than 1gm/min and greater than 3 gm/min in different embodiments. Ozone may beflowed at greater than 1,000 sccm, greater than 3,000 sccm, greater than10,000 sccm or greater than 30,000 sccm in different embodiments.Relatively inert carrier gases may be used to deliver the TEOS andoptional additives to the substrate and the masses of the carrier gasare not included in the gm/min delivery rates given above.

The method continues and includes providing a carbon-freesilicon-containing precursor to a substrate processing region (operation102). The carbon-free silicon-containing precursor may be, for example,a silicon-and-nitrogen precursor, a silicon-and-hydrogen precursor, or asilicon-nitrogen-and-hydrogen-containing precursor, among other classesof silicon precursors. The silicon-precursor may be oxygen-free inaddition to carbon-free. The lack of oxygen results in a lowerconcentration of silanol (Si—OH) groups in the silicon-and-nitrogenlayer formed from the precursors. Excess silanol moieties in thedeposited film can cause increased porosity and shrinkage during postdeposition steps that remove the hydroxyl (—OH) moieties from thedeposited layer.

Specific examples of carbon-free silicon-containing precursors mayinclude silyl-amines such as H₂N(SiH₃), HN(SiH₃)₂, and N(SiH₃)₃, amongother silyl-amines. The flow rates of a silyl-amine may be greater thanor about 200 sccm, greater than or about 300 sccm or greater than orabout 500 sccm in different embodiments. All flow rates given hereinrefer to a dual chamber substrate processing system. Single wafersystems would require half these flow rates and other wafer sizes wouldrequire flow rates scaled by the processed area. These silyl-amines maybe mixed with additional gases that may act as carrier gases, reactivegases, or both. Examples of these additional gases may include H₂, N₂,NH₃, He, and Ar, among other gases. Examples of carbon-freesilicon-containing precursors may also include silane (SiH₄) eitheralone or mixed with other silicon (e.g., N(SiH₃)₃), hydrogen (e.g., H₂),and/or nitrogen (e.g., N₂, NH₃) containing gases. Carbon-freesilicon-containing precursors may also include disilane, trisilane, evenhigher-order silanes, and chlorinated silanes, alone or in combinationwith one another or the previously mentioned carbon-freesilicon-containing precursors. The carbon-free silicon-containingprecursor is not excited in a plasma region (e.g. a remote plasmaregion) before entering the plasma-free substrate processing region.

Ammonia (NH₃) is delivered to a plasma region to form a radical-nitrogenprecursor (operation 104). The radical-nitrogen precursor is anitrogen-radical-containing precursor generated in the plasma regionoutside the substrate processing region from the ammonia. For example,the stable nitrogen precursor compound containing NH₃ may be activatedin a chamber plasma region or a remote plasma system (RPS) outside theprocessing chamber to form the radical-nitrogen precursor, which is thentransported into the substrate processing region (operation 106). Theflow rate of the ammonia may be greater than or about 300 sccm, greaterthan or about 500 sccm or greater than or about 700 sccm in differentembodiments while additional precursors such as nitrogen (N₂) andhydrogen (H₂) may be included to adjust the nitrogen:hydrogen atomicflow ratio. The radical-nitrogen precursor may also be produced withoutusing NH₃. Stable nitrogen precursors flowed into the remote plasmaregion may include one or more of H₂, N₂ and N₂H₄, in embodiments of theinvention. The radical-nitrogen precursor produced in the chamber plasmaregion may be one or more of .N, .NH, .NH₂, etc., and may also beaccompanied by ionized species formed in the plasma.

In embodiments employing a chamber plasma region, the radical-nitrogenprecursor is generated in a section of the substrate processing systempartitioned from a substrate processing region where the precursors mixand react to deposit the silicon-and-nitrogen layer on a depositionsubstrate (e.g., a semiconductor wafer). The radical-nitrogen precursormay also be accompanied by a carrier gas such as helium, argon etc. Thesubstrate processing region may be described herein as “plasma-free”during the growth of the silicon-and-nitrogen-containing layer andduring the low temperature ozone cure. “Plasma-free” does notnecessarily mean the region is devoid of plasma. Ionized species createdwithin the plasma region do travel through pores (apertures) in thepartition (showerhead) but the carbon-free silicon-containing precursoris not substantially excited by the plasma power applied to the plasmaregion. The borders of the plasma in the chamber plasma region are hardto define and may encroach upon the substrate processing region throughthe apertures in the showerhead. In the case of an inductively-coupledplasma, a small amount of ionization may be effected within thesubstrate processing region directly. Furthermore, a low intensityplasma may be created in the substrate processing region withouteliminating the flowable nature of the forming film. Plasmas in thesubstrate processing region having much lower ion density than thechamber plasma region during the creation of the radical nitrogenprecursor do not deviate from the scope of “plasma-free” as used herein.

In the substrate processing region, the carbon-free silicon-containingprecursor and the radical-nitrogen precursor mix and react to form asilicon-and-nitrogen-containing film on the deposition substrate(operation 108). The deposited silicon-and-nitrogen-containing film maydeposit conformally with recipe combinations which result in lowdeposition rates or high radical nitrogen fluxes at the depositionsurface. In other embodiments, the depositedsilicon-and-nitrogen-containing film has flowable characteristics unlikeconventional silicon nitride (Si₃N₄) film deposition techniques. Theflowable nature of the formation allows the film to flow into narrowgaps trenches and other structures on the deposition surface of thesubstrate. The temperature of the substrate during deposition (operation108) is less than 120° C., less than 100° C., less than 80° C. and lessthan 60° C. in different embodiments.

The flowability may be due to a variety of properties which result frommixing a radical-nitrogen precursors with the unexcited carbon-freesilicon-containing precursor. These properties may include a significanthydrogen component in the deposited film and/or the presence of shortchained polysilazane polymers. These short chains grow and network toform more dense dielectric material during and after the formation ofthe film. For example the deposited film may have a silazane-type,Si—NH—Si backbone (i.e., a Si—N—H film). When both thesilicon-containing precursor and the radical-nitrogen precursor arecarbon-free, the deposited silicon-and-nitrogen-containing film is alsosubstantially carbon-free. Of course, “carbon-free” does not necessarilymean the film lacks even trace amounts of carbon. Carbon contaminantsmay be present in the precursor materials that find their way into thedeposited silicon-and-nitrogen precursor. The amount of these carbonimpurities however are much less than would be found in asilicon-containing precursor having a carbon moiety (e.g., TEOS, TMDSO,etc.), for example, in the liner layer grown in operation 101.

Following the deposition of the silicon-and-nitrogen-containing layer,the deposition substrate may be cured and/or annealed inoxygen-containing atmosphere(s) (operation 110). The curing may occur inan ozone-containing atmosphere at a substrate temperature below or about400° C. Under some conditions (e.g. between substrate temperatures fromabout 100° C. to about 200° C.) the conversion has been found to besubstantially complete so a relatively high temperature anneal in anoxygen-containing environment may be unnecessary in embodiments of theinvention. Following curing of the silicon-and-nitrogen containinglayer, it may be desirable to anneal the substrate in anoxygen-containing atmosphere to further convert the film to siliconoxide. The oxygen-containing atmosphere may include one or moreoxygen-containing gases such as molecular oxygen (O₂), ozone (O₃), watervapor (H₂O), hydrogen peroxide (H₂O₂) and nitrogen-oxides (NO, NO₂,etc.), among other oxygen-containing gases. The oxygen-containingatmosphere may also include radical oxygen and hydroxyl species such asatomic oxygen (O), hydroxides (OH), etc., that may be generated remotelyand transported into the substrate chamber. Ions of oxygen-containingspecies may also be present. The oxygen anneal temperature of thesubstrate may be between about 500° C. and about 1100° C. When a plasmais used, it may be in the substrate processing region, in a separateregion separated by a showerhead or in a remote plasma system (RPS).

The oxygen-containing atmospheres of both the curing and oxygen annealprovide oxygen to convert the silicon-and-nitrogen-containing film intothe silicon oxide (SiO₂) film. As noted previously, the lack of carbonin the silicon-and-nitrogen-containing film results in significantlyfewer pores formed in the final silicon oxide film. It also results inless volume reduction (i.e., shrinkage) of the film during theconversion to the silicon oxide. For example, where asilicon-nitrogen-carbon layer formed from carbon-containing siliconprecursors and radical-nitrogen may shrink by 40 vol. % or more whenconverted to silicon oxide, the substantially carbon-freesilicon-and-nitrogen films may shrink by about 17 vol. % or less.

Referring now to FIG. 2, another flowchart is shown illustratingselected steps in methods 200 for forming a silicon oxide film in asubstrate gap according to embodiments of the invention. The method 200includes depositing a silicon oxide liner on a patterned substratehaving gaps in the spacing and structure of device components (e.g.,transistors) formed on the substrate. The gaps may have a height andwidth that define an aspect ratio (AR) of the height to the width (i.e.,H/W) that is significantly greater than 1:1 (e.g., 5:1 or more, 6:1 ormore, 7:1 or more, 8:1 or more, 9:1 or more, 10:1 or more, 11:1 or more,12:1 or more, etc.). In many instances the high AR is due to small gapwidths of that range from about 90 nm to about 22 nm or less (e.g.,about 90 nm, 65 nm, 45 nm, 32 nm, 22 nm, 16 nm, etc.).

The silicon oxide liner is deposited with concurrent flows of TEOS andoxygen (O₂) (operation 201). Substrate temperatures may be the same asthe embodiments described with reference to FIG. 1 and the sameadditives may be added for the same purposes. The relatively highdeposition temperature allows the deposition to proceed more rapidlythan if the radical-component deposition were attempted without theliner layer. The liner presents a silicon oxide surface which is lessinert and more conducive to relatively low-temperature deposition. Suchdeposition processes are known in the art as sub-atmospheric CVD (SACVD)but may also be conducted at pressures in excess of 1 atm. Exemplaryflow-rates of TEOS may be greater than 0.1 gm/min (grams per minute),greater than 0.5 gm/min, greater than 1 gm/min and greater than 3 gm/minin different embodiments. Oxygen may be flowed at greater than 3,000sccm, greater than 10,000 sccm, greater than 30,000 sccm or greater than60,000 sccm in different embodiments. Relatively inert carrier gases areused to deliver the TEOS and optional additives to the substrate and themasses of the carrier gas are not included in the gm/min delivery ratesgiven above.

The substrate is then transferred to a substrate processing region(operation 202) and ammonia (NH₃) is excited in a separate chamberplasma region to form a radical-nitrogen precursor 204. A plasma in thechamber plasma region creates the radical-nitrogen precursor which flowsthrough apertures in a showerhead separating the chamber plasma regionfrom the substrate processing region. A carbon-free silicon-containingprecursor is mixed with the radical nitrogen precursor in the substrateprocessing region (operation 206). A flowablesilicon-and-nitrogen-containing layer is deposited on the substrate(operation 208). Because the layer is flowable, it can fill the gapshaving the high aspect ratios without creating voids or weak seamsaround the center of the filling material. For example, a depositingflowable material is less likely to prematurely clog the top of a gapbefore it is completely filled to leave a void in the middle of the gap.The substrate temperature is below the temperatures discussed withreference to FIG. 1 in embodiments.

The as-deposited silicon-and-nitrogen-containing layer may then be curedin an ozone-containing atmosphere and/or annealed in anoxygen-containing atmosphere (operation 210) to transition thesilicon-and-nitrogen-containing layer to silicon oxide. A further anneal(not shown) may be carried out in an inert environment at a highersubstrate temperature in order to densify the silicon oxide layer.Curing and annealing the as-deposited silicon-and-nitrogen-containinglayer in an oxygen-containing atmosphere forms a silicon oxide layer onthe substrate, including the substrate gap. In embodiments, theprocessing parameters of operation 210 possess the same ranges describedwith reference to FIG. 1. As noted above, the silicon oxide layer hasfewer pores and less volume reduction than similar layers formed withcarbon-containing precursors that have significant quantities of carbonpresent in the layer before the heat treatment step. In many cases, thevolume reduction is slight enough (e.g., about 15 vol. % or less) toavoid post heat treatment steps to fill, heal, or otherwise eliminatespaces that form in the gap as a result of the shrinking silicon oxide.

Exemplary Silicon Oxide Deposition System

Deposition chambers that may implement embodiments of the presentinvention may include high-density plasma chemical vapor deposition(HDP-CVD) chambers, plasma enhanced chemical vapor deposition (PECVD)chambers, sub-atmospheric chemical vapor deposition (SACVD) chambers,and thermal chemical vapor deposition chambers, among other types ofchambers. Specific examples of CVD systems that may implementembodiments of the invention include the CENTURA ULTIMA® HDP-CVDchambers/systems, and PRODUCER® PECVD chambers/systems, available fromApplied Materials, Inc. of Santa Clara, Calif.

Examples of substrate processing chambers that can be used withexemplary methods of the invention may include those shown and describedin co-assigned U.S. Provisional Patent App. No. 60/803,499 to Lubomirskyet al, filed May 30, 2006, and titled “PROCESS CHAMBER FOR DIELECTRICGAPFILL,” the entire contents of which is herein incorporated byreference for all purposes. Additional exemplary systems may includethose shown and described in U.S. Pat. Nos. 6,387,207 and 6,830,624,which are also incorporated herein by reference for all purposes.

Embodiments of the deposition systems may be incorporated into largerfabrication systems for producing integrated circuit chips. FIG. 3 showsone such system 300 of deposition, baking and curing chambers accordingto disclosed embodiments. In the figure, a pair of FOUPs (front openingunified pods) 302 supply substrate substrates (e.g., 300 mm diameterwafers) that are received by robotic arms 304 and placed into a lowpressure holding area 306 before being placed into one of the waferprocessing chambers 308 a-f. A second robotic arm 310 may be used totransport the substrate wafers from the holding area 306 to theprocessing chambers 308 a-f and back.

The processing chambers 308 a-f may include one or more systemcomponents for depositing, annealing, curing and/or etching a flowabledielectric film on the substrate wafer. In one configuration, two pairsof the processing chamber (e.g., 308 c-d and 308 e-f) may be used todeposit the flowable dielectric material on the substrate, and the thirdpair of processing chambers (e.g., 308 a-b) may be used to anneal thedeposited dielectic. In another configuration, the same two pairs ofprocessing chambers (e.g., 308 c-d and 308 e-f) may be configured toboth deposit and anneal a flowable dielectric film on the substrate,while the third pair of chambers (e.g., 308 a-b) may be used for UV orE-beam curing of the deposited film. In still another configuration, allthree pairs of chambers (e.g., 308 a-f) may be configured to deposit andcure a flowable dielectric film on the substrate. In yet anotherconfiguration, two pairs of processing chambers (e.g., 308 c-d and 308e-f) may be used for both deposition and UV or E-beam curing of theflowable dielectric, while a third pair of processing chambers (e.g. 308a-b) may be used for annealing the dielectric film. Any one or more ofthe processes described may be carried out on chamber(s) separated fromthe fabrication system shown in different embodiments.

In addition, one or more of the process chambers 308 a-f may beconfigured as a wet treatment chamber. These process chambers includeheating the flowable dielectric film in an atmosphere that includemoisture. Thus, embodiments of system 300 may include wet treatmentchambers 308 a-b and anneal processing chambers 308 c-d to perform bothwet and dry anneals on the deposited dielectric film.

A silicon oxide liner layer may deposited in one of the chambers whichis configured to deposit a liner layer via sub-atmospheric chemicalvapor deposition (SACVD). Other names may be used to describe relativelyhigh pressure processes involving exposure of the substrate to acombination of TEOS and ozone or TEOS and oxygen (O₂). Such systems arealso available from Applied Materials, Inc. of Santa Clara, Calif. Thesilicon oxide liner layer thickness may be less than 100 Å, less than 75Å, less than 50 Å and less than 25 Å in different embodiments. Followingdeposition of a silicon oxide liner layer, the substrate may betransferred to a radical-component CVD chamber as described in FIG. 4.Alternatively, a spin-on dielectric (SOD), spin-on glass (SOG) or otherspin-on silicon-containing film may be applied. Spin-on flowablematerials will offer similar benefits to radical-component flowabledeposition in that the film will exhibit less delamination and crackingSOD films containing silicon and nitrogen will exhibit these benefits inembodiments of the invention.

FIG. 4A is a substrate processing chamber 400 according to disclosedembodiments. A remote plasma system (RPS) 410 may process a gas whichthen travels through a gas inlet assembly 411. Two distinct gas supplychannels are visible within the gas inlet assembly 411. A first channel412 carries a gas that passes through the remote plasma system RPS 410,while a second channel 413 bypasses the RPS 400. The first channel 402may be used for the process gas and the second channel 413 may be usedfor a treatment gas in disclosed embodiments. The lid (or conductive topportion) 421 and a perforated partition 453 are shown with an insulatingring 424 in between, which allows an AC potential to be applied to thelid 421 relative to perforated partition 453. The process gas travelsthrough first channel 412 into chamber plasma region 420 and may beexcited by a plasma in chamber plasma region 420 alone or in combinationwith RPS 410. The combination of chamber plasma region 420 and/or RPS410 may be referred to as a remote plasma system herein. The perforatedpartition (also referred to as a showerhead) 453 separates chamberplasma region 420 from a substrate processing region 470 beneathshowerhead 453. Showerhead 453 allows a plasma present in chamber plasmaregion 420 to avoid directly exciting gases in substrate processingregion 470, while still allowing excited species to travel from chamberplasma region 420 into substrate processing region 470.

Showerhead 453 is positioned between chamber plasma region 420 andsubstrate processing region 470 and allows plasma effluents (excitedderivatives of precursors or other gases) created within chamber plasmaregion 420 to pass through a plurality of through holes 456 thattraverse the thickness of the plate. The showerhead 453 also has one ormore hollow volumes 451 which can be filled with a precursor in the formof a vapor or gas (such as a silicon-containing precursor) and passthrough small holes 455 into substrate processing region 470 but notdirectly into chamber plasma region 420. Showerhead 453 is thicker thanthe length of the smallest diameter 450 of the through-holes 456 in thisdisclosed embodiment. In order to maintain a significant concentrationof excited species penetrating from chamber plasma region 420 tosubstrate processing region 470, the length 426 of the smallest diameter450 of the through-holes may be restricted by forming larger diameterportions of through-holes 456 part way through the showerhead 453. Thelength of the smallest diameter 450 of the through-holes 456 may be thesame order of magnitude as the smallest diameter of the through-holes456 or less in disclosed embodiments.

In the embodiment shown, showerhead 453 may distribute (via throughholes 456) process gases which contain oxygen, hydrogen and/or nitrogenand/or plasma effluents of such process gases upon excitation by aplasma in chamber plasma region 420. In embodiments, process gasesexcited in RPS 410 and/or chamber plasma region 420 include ammonia(NH₃) and nitrogen (N₂) and/or hydrogen (H₂). Generally speaking, theprocess gas introduced into the RPS 410 and/or chamber plasma region 420through first channel 412 may contain one or more of oxygen (O₂), ozone(O₃), N₂O, NO, NO₂, NH₃, N_(x)H_(y) including N₂H₄, silane, disilane,TSA and DSA. The process gas may also include a carrier gas such ashelium, argon, nitrogen (N₂), etc. The second channel 413 may alsodeliver a process gas and/or a carrier gas, and/or a film-curing gasused to remove an unwanted component from the growing or as-depositedfilm. Plasma effluents may include ionized or neutral derivatives of theprocess gas and may also be referred to herein as a radical-oxygenprecursor and/or a radical-nitrogen precursor referring to the atomicconstituents of the process gas introduced.

In embodiments, the number of through-holes 456 may be between about 60and about 2000. Through-holes 456 may have a variety of shapes but aremost easily made round. The smallest diameter 450 of through holes 456may be between about 0.5 mm and about 20 mm or between about 1 mm andabout 6 mm in disclosed embodiments. There is also latitude in choosingthe cross-sectional shape of through-holes, which may be made conical,cylindrical or a combination of the two shapes. The number of smallholes 455 used to introduce a gas into substrate processing region 470may be between about 100 and about 5000 or between about 500 and about2000 in different embodiments. The diameter of the small holes 455 maybe between about 0.1 mm and about 2 mm.

FIG. 4B is a bottom view of a showerhead 453 for use with a processingchamber according to disclosed embodiments. Showerhead 453 correspondswith the showerhead shown in FIG. 4A. Through-holes 456 are depictedwith a larger inner-diameter (ID) on the bottom of showerhead 453 and asmaller ID at the top. Small holes 455 are distributed substantiallyevenly over the surface of the showerhead, even amongst thethrough-holes 456 which helps to provide more even mixing than otherembodiments described herein.

An exemplary film is created on a substrate supported by a pedestal (notshown) within substrate processing region 470 when plasma effluentsarriving through through-holes 456 in showerhead 453 combine with asilicon-containing precursor arriving through the small holes 455originating from hollow volumes 451. Though substrate processing region470 may be equipped to support a plasma for other processes such ascuring, no plasma is present during the growth of the exemplary film.

A plasma may be ignited either in chamber plasma region 420 aboveshowerhead 453 or substrate processing region 470 below showerhead 453.A plasma is present in chamber plasma region 420 to produce the radicalnitrogen precursor from an inflow of a nitrogen-and-hydrogen-containinggas. An AC voltage typically in the radio frequency (RF) range isapplied between the conductive top portion 421 of the processing chamberand showerhead 453 to ignite a plasma in chamber plasma region 420during deposition. An RF power supply generates a high RF frequency of13.56 MHz but may also generate other frequencies alone or incombination with the 13.56 MHz frequency.

The top plasma may be left at low or no power when the bottom plasma inthe substrate processing region 470 is turned on to either cure a filmor clean the interior surfaces bordering substrate processing region470. A plasma in substrate processing region 470 is ignited by applyingan AC voltage between showerhead 453 and the pedestal or bottom of thechamber. A cleaning gas may be introduced into substrate processingregion 470 while the plasma is present.

The pedestal may have a heat exchange channel through which a heatexchange fluid flows to control the temperature of the substrate. Thisconfiguration allows the substrate temperature to be cooled or heated tomaintain relatively low temperatures (from room temperature throughabout 120° C.). The heat exchange fluid may comprise ethylene glycol andwater. The wafer support platter of the pedestal (preferably aluminum,ceramic, or a combination thereof) may also be resistively heated inorder to achieve relatively high temperatures (from about 120° C.through about 1100° C.) using an embedded single-loop embedded heaterelement configured to make two full turns in the form of parallelconcentric circles. An outer portion of the heater element may runadjacent to a perimeter of the support platter, while an inner portionruns on the path of a concentric circle having a smaller radius. Thewiring to the heater element passes through the stem of the pedestal.

The substrate processing system is controlled by a system controller. Inan exemplary embodiment, the system controller includes a hard diskdrive, a floppy disk drive and a processor. The processor contains asingle-board computer (SBC), analog and digital input/output boards,interface boards and stepper motor controller boards. Various parts ofCVD system conform to the Versa Modular European (VME) standard whichdefines board, card cage, and connector dimensions and types. The VMEstandard also defines the bus structure as having a 16-bit data bus anda 24-bit address bus.

The system controller controls all of the activities of the CVD machine.The system controller executes system control software, which is acomputer program stored in a computer-readable medium. Preferably, themedium is a hard disk drive, but the medium may also be other kinds ofmemory. The computer program includes sets of instructions that dictatethe timing, mixture of gases, chamber pressure, chamber temperature, RFpower levels, susceptor position, and other parameters of a particularprocess. Other computer programs stored on other memory devicesincluding, for example, a floppy disk or other another appropriatedrive, may also be used to instruct the system controller.

A process for depositing a film stack on a substrate or a process forcleaning a chamber can be implemented using a computer program productthat is executed by the system controller. The computer program code canbe written in any conventional computer readable programming language:for example, 68000 assembly language, C, C++, Pascal, Fortran or others.Suitable program code is entered into a single file, or multiple files,using a conventional text editor, and stored or embodied in a computerusable medium, such as a memory system of the computer. If the enteredcode text is in a high level language, the code is compiled, and theresultant compiler code is then linked with an object code ofprecompiled Microsoft Windows® library routines. To execute the linked,compiled object code the system user invokes the object code, causingthe computer system to load the code in memory. The CPU then reads andexecutes the code to perform the tasks identified in the program.

The interface between a user and the controller is via a flat-paneltouch-sensitive monitor. In the preferred embodiment two monitors areused, one mounted in the clean room wall for the operators and the otherbehind the wall for the service technicians. The two monitors maysimultaneously display the same information, in which case only oneaccepts input at a time. To select a particular screen or function, theoperator touches a designated area of the touch-sensitive monitor. Thetouched area changes its highlighted color, or a new menu or screen isdisplayed, confirming communication between the operator and thetouch-sensitive monitor. Other devices, such as a keyboard, mouse, orother pointing or communication device, may be used instead of or inaddition to the touch-sensitive monitor to allow the user to communicatewith the system controller.

As used herein “substrate” may be a support substrate with or withoutlayers formed thereon. The support substrate may be an insulator or asemiconductor of a variety of doping concentrations and profiles andmay, for example, be a semiconductor substrate of the type used in themanufacture of integrated circuits. A layer of “silicon oxide” mayinclude minority concentrations of other elemental constituents such asnitrogen, hydrogen, carbon and the like. A gas in an “excited state”describes a gas wherein at least some of the gas molecules are invibrationally-excited, dissociated and/or ionized states. A gas may be acombination of two or more gases. The term “trench” is used throughoutwith no implication that the etched geometry has a large horizontalaspect ratio. Viewed from above the surface, trenches may appearcircular, oval, polygonal, rectangular, or a variety of other shapes.The term “via” is used to refer to a low aspect ratio trench which mayor may not be filled with metal to form a vertical electricalconnection. The term “precursor” is used to refer to any process gaswhich takes part in a reaction to either remove or deposit material froma surface.

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent invention. Accordingly, the above description should not betaken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the precursor” includesreference to one or more precursor and equivalents thereof known tothose skilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

What is claimed is:
 1. A method of forming a flowable dielectric layeron a substrate, the method comprising the sequential steps of: forming agenerally conformal silicon oxide liner layer on silicon nitride on thesubstrate by exposing the substrate to a silicon-containing linerprecursor and an oxygen-containing liner precursor, wherein thesubstrate is maintained at a liner deposition temperature; forming acarbon-free flowable silicon-nitrogen-and-hydrogen-containing layer onthe silicon oxide liner layer using radical-component chemical vapordeposition, wherein the substrate is maintained at a bulk depositiontemperature, wherein the bulk-deposition temperature is less than 120°C.; curing the substrate at a substrate temperature below or about 400°C. in an ozone-containing atmosphere, and raising a temperature of thesubstrate to an oxygen anneal temperature above or about 600° C. in anoxygen-containing atmosphere.
 2. The method of claim 1 wherein formingthe carbon-free flowable silicon-nitrogen-and-hydrogen-containing layercomprises: flowing a nitrogen-and-hydrogen-containing gas into a plasmaregion to produce a radical-nitrogen precursor; combining a carbon-freesilicon-containing precursor with the radical-nitrogen precursor in aplasma-free substrate processing region; and depositing asilicon-and-nitrogen-containing layer on the substrate.
 3. The method ofclaim 2 wherein the nitrogen-and-hydrogen-containing gas comprisesammonia (NH₃).
 4. The method of claim 2 wherein thenitrogen-and-hydrogen-containing gas comprises at least one of nitrogen(N₂), hydrogen (H₂), hydrazine (N₂H₄) and ammonia (NH₃).
 5. The methodof claim 1 wherein a thickness of the generally conformal silicon oxideliner is less than or about 100 Å.
 6. The method of claim 2 wherein thecarbon-free silicon-containing precursor comprises N(SiH₃)₃.
 7. Themethod of claim 1 wherein the carbon-free flowablesilicon-nitrogen-and-hydrogen-containing layer comprises a carbon-freeSi—N—H layer.
 8. The method of claim 1 wherein the bulk-depositiontemperature is lower than the liner deposition temperature.
 9. Themethod of claim 1 wherein the oxygen-containing liner precursorcomprises oxygen (O₂).
 10. The method of claim 1 wherein the linerdeposition temperature is greater than 400° C.
 11. The method of claim 1wherein the silicon-containing liner precursor comprises TEOS.
 12. Themethod of claim 1 wherein the oxygen-containing atmosphere comprises oneor more gases selected from the group consisting of atomic oxygen,ozone, and steam (H₂O).
 13. The method of claim 2 wherein the plasmaregion is in a remote plasma system.
 14. The method of claim 2 whereinthe plasma region is a partitioned portion of the substrate processingchamber separated from the plasma-free substrate processing region by ashowerhead.
 15. The method of claim 1 wherein the oxygen-containingliner precursor comprises ozone.